Valve system

ABSTRACT

The present specification is directed to a valve that has an orifice closing member adjacent to an orifice through which fluid can flow, a displacement member having a first portion and a second portion, where the first portion is adjacent to the orifice closing member when the valve is in an open position, a first magnet and a second magnet where the first and second magnets are sufficiently proximate to the displacement member to exert a magnetic force on the displacement member, and an actuator for generating a magnetic field to move the displacement member toward the first magnet, cause the first portion to press against the orifice closing member, and cause the orifice closing member to close the orifice.

CROSS-REFERENCE

The present application is a continuation of U.S. patent applicationSer. No. 12/351,969, entitled “Valve System”, which was filed on Jan.12, 2009.

FIELD

The present specification generally relates to the field of valves andmore specifically to an electrically driven, magnetic valve for use inkidney dialysis systems where low power consumption, low heatgeneration, high reliability and a small, light size are functionalrequirements.

BACKGROUND

Valves are widely used to control the flow of fluids through systems.Valve requirements vary dramatically depending upon the nature and scopeof the application. In a kidney dialysis system, particularly portablekidney dialysis systems, the functional requirements for a valve includelow power consumption, low heat generation, high reliability and asmall, light size.

Typically, automated valves in kidney dialysis systems require energyinput to maintain at least one state, namely an open state or closedstate. However, the on-going need for energy input to maintain a statehas substantial disadvantages. First, the system requires a higheramount of energy, thereby decreasing system mobility. Second, a systemfailure can cause a cut off in energy supply, thereby adverselyaffecting the state of a valve and causing a major secondary systemfailure that can hurt a kidney dialysis patient.

Valves that operate between two states (open and closed) in which energyinput is required to change a state, but not to maintain a state, areknown. For example, U.S. Pat. Nos. 6,836,201, 5,322,258, 6,517,045, and7,314,208 all of which are incorporated by reference, disclose valves inwhich energy input is required to change a state, but not to maintain astate. However, these valve systems have not been applied, or weresuggested to be applied, to the field of kidney dialysis. Moreover, theyare typically not suitable for reliably maintaining the valve's closedstate at the size dimensions, reliability, and force levels required bykidney dialysis systems.

In sum, valves disclosed in the medical, and more specifically kidneydialysis, fields of art are not suitable to effectively meet theaforementioned functional needs. Accordingly there is need in the priorart for an improved valve with the aforementioned attributes.

SUMMARY

In one embodiment, the present specification is directed to a valvehaving an open position and a closed position comprising an orificeclosing member adjacent to an orifice through which fluid can flow, adisplacement member having a first portion and a second portion, whereinsaid first portion is adjacent to the orifice closing member when thevalve is in said open position, a first magnet and a second magnetwherein said first and second magnets are sufficiently proximate to saiddisplacement member to exert a magnetic force on said displacementmember, and an actuator for generating a magnetic field to move saiddisplacement member toward said first magnet, cause said first portionto press against the orifice closing member, and cause the orificeclosing member to close said orifice.

Optionally, the first portion comprises a housing, compliant material,such as a spring, a rod and a gap between the compliant material and therod. The valve further comprises an optical sensor positioned to senseif a gap in said valve is present or absent. The first portion comprisesa rod and the second portion of the displacement member is a metal bodywith a diameter greater than said rod. The rod is bonded to saidcylinder. The first magnet is larger than said second magnet. Theorifice closing member comprises at least one of a diaphragm, an elasticmaterial, a compliant material and a compressible material. The orificeis part of a manifold for a kidney dialysis system. The orifice closingmember compresses against a valve seat to close said orifice. The valveseat is part of a manifold for a kidney dialysis system. The orificeclosing member is part of a manifold for a kidney dialysis system.

In another embodiment, the valve comprises a) an orifice closing memberadjacent to an orifice through which fluid can flow wherein said orificeclosing member compresses against a valve seat when the valve is in aclosed position, b) a moveable member that is physically movablerelative to said orifice closing member wherein said moveable membermoves from a first position when said valve is in an open position to asecond position when said valve is in said closed position and wherein,in said second position, the moveable member presses against the orificeclosing member to cause said orifice closing member to compress againstthe valve seat, c) a first magnet and a second magnet having aseparation wherein said first magnet and second magnet generate amagnetic field in the separation and wherein said magnetic field has adirection; and d) an actuator capable of generating an electromagneticforce, wherein said electromagnetic force reverses the direction of saidmagnetic field.

Optionally, the valve further comprises an optical sensor positioned tosense if a gap is present or absent. The moveable member comprises a rodand a cylinder with a diameter greater than the rod, along with acompliant material, such as a spring. The first magnet is larger thanthe second magnet. The orifice closing member and valve seat are part ofa disposable manifold for a kidney dialysis system.

In another embodiment, the valve comprises a) a diaphragm, b) a valveseat adjacent to the diaphragm, wherein, when the valve is in a closedstate, said diaphragm compresses against the valve seat and causes asealing of the orifice through which fluid can flow and wherein, whenthe valve is in an open state, the diaphragm does not compress againstthe valve seat, c) a displacement member comprising a rod bonded to acylinder wherein said displacement member is moveable relative to thediaphragm, wherein the rod does not compress the diaphragm when thevalve is in the open position, and wherein the rod compresses thediaphragm when the valve is in the closed position, d) a first magnetand a second magnet wherein the first magnet is larger than the secondmagnet, wherein the first magnet exerts a greater magnetic force on thecylinder than the second magnet when the valve is in the closed positionand wherein the second magnet exerts a greater magnetic force on thecylinder than the first magnet when the valve is in the open position,and e) an actuator for generating the magnetic force exerted by saidfirst magnet on said cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the inventions disclosedherein will be appreciated, as they become better understood byreference to the following detailed description when considered inconnection with the accompanying drawings, wherein:

FIG. 1 depicts an embodiment of a valve of the present inventions wherethe valve is in an open state;

FIG. 2 depicts an embodiment of a valve of the present inventions wherethe valve is in a closed stated;

FIG. 3 is a diagram of one embodiment of the actuator;

FIG. 4 shows a schematic diagram of another embodiment of a displacementmember and mechanism of the present inventions;

FIG. 5 is a schematic illustration of one embodiment of the displacementsystem of the present invention when the valve is in an open state;

FIG. 6 is a chart showing an exemplary relationship between the force onone embodiment of an orifice compressing member and its displacement;

FIG. 7 is a schematic illustration of one embodiment of the displacementsystem of the present invention when the valve is in a closed state; and

FIG. 8 is a flowchart describing steps for how the valve opens andcloses.

DETAILED DESCRIPTION

While the present specification may be embodied in many different forms,for the purpose of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended. Any alterations and further modificationsin the described embodiments, and any further applications of theprinciples of the invention as described herein are contemplated aswould normally occur to one skilled in the art to which the inventionrelates.

The present specification discloses a system that functions as a fluidicvalve in a kidney dialysis system, such as a portable kidney dialysissystem. The system comprises a magnetic displacement system that islightweight and consumes minimum power, making it ideal even when theportable kidney dialysis system uses a disposable manifold for fluidiccircuits. The system can be used in conjunction with an orifice in anystructure. In particular, an orifice is any hole, opening, void, orpartition in any type of material. This includes pathways in tubing,manifolds, disposable manifolds, channels, and other pathways. U.S.patent Ser. Nos. 12/324,924, 12/237,914, and 12/245,397, co-owned by thepresent applicant, disclose exemplary manifolds with which the presentinvention can be implemented and are incorporated herein by reference.One of ordinary skill in the art would appreciate that the presentlydisclosed valve system would be implemented with a disposable manifoldby positioning the displacement member and magnets, as further discussedbelow, external to the manifold at the desired valve location. Theactuator is also separate and distinct from the disposable manifold andgenerally part of the non-disposable portion of the kidney dialysissystem.

Functionally, the valve has two stable states: open and closed. Itoperates by using magnetic forces to move a displacement member againsta diaphragm and thereby create sufficient force to press the diaphragmagainst a valve seat and cause the diaphragm to close the orifice.Closing of the orifice shuts off fluid flow. The reverse process, namelythe use of magnetic forces to move a displacement member away from thediaphragm and thereby release the diaphragm from compression against thevalve seat, opens the orifice and permits fluid to flow.

It should be appreciated that while the inventions shall be discussed interms of a preferred embodiment, depicted in FIGS. 1 and 2, and anon-preferred embodiment, depicted in FIG. 4, the present invention isgenerally directed to any use of a valve in a kidney dialysis systemhaving the following attributes: a) two stable states, open and closed,b) changing states requires energy input, c) maintaining a state doesnot require energy input, d) a state is changed by the use of magneticforces to modify the position of a displacement member which, whenmodified, causes a valve to either open or close.

In one embodiment, referring to FIG. 1, the valve system of the presentinvention 100 is used to control fluid flow through a fluidic flowchannel 102, which is bounded by valve seats 104 to thereby create avalve annular orifice 103. As discussed above, orifice 101 is any hole,opening, void, or partition in any type of material, in particular,manifolds, disposable manifolds, channels, and other pathways 110. Thevalve 100 is shown in an open state. The components of the valve systeminclude an orifice closing member, a displacement member, a mechanismfor moving the displacement member, an optional optical sensor, a coildriver circuit, and an actuator having a coil.

In one embodiment, the orifice closing member comprises a diaphragm 106which, when compressed by the displacement member, as discussed below,presses against the valve seats 104, thereby causing the valve annularorifice 103, to close. In an open state, the main body of the diaphragm106 is separated from the valve seats 104 by a gap 198. In oneembodiment, the diaphragm 106 is made from a soft material such assilicone rubber. The diaphragm 106 must maintain its shape over time,temperature, and actuations. The valve 100 relies upon the diaphragmmaterial 106 to return to its uncompressed shape when the displacementmember (compressing force) is removed, the open state.

One of ordinary skill in the art should appreciate that the orificeclosing member can comprise any combination of spring, compressible, ornon-compressible structures which, when pushed by the displacementmember, closes the orifice. In one embodiment, the valve seats 104 canbe molded into a manifold. Suitable materials for the valve seat arepolycarbonate, ABS and similar plastics. The valve orifice 103 in thepreferred embodiment ranges from 0.1 to 0.3 inches in diameter (and moreparticularly 0.190 inches). Orifice dimensions can be increased toincrease flow for alternate applications of the invention or,alternatively, decreased to decrease flow for alternate applications.

In one embodiment, the displacement member comprises a plunger cap, orhousing, 110, which, when the valve is in an open state, is alignedagainst the diaphragm 106, but not substantially compressing thediaphragm 106. Positioned inside the plunger cap 110 is a compliantcomponent, such as a spring, 112 and the head of plunger 199, which areseparated by an air gap 114. The plunger cap 110 is encompassed bound onthe outside by a fluid seal 120, which in one embodiment, is a thin,soft silicone rubber washer. In one embodiment, the plunger cap 110 isforced against the silicone rubber washer and compresses the washer toform the fluid seal 120. When in a closed position, the plunger cap 110is not forced against the washer, which is therefore not compressed andpositioned loose to the end cap 130. The spring 112 is any elastic orcompliant material and, in one embodiment, comprises a waves spring.

The plunger cap 110, internal spring 112, air gap, plunger head 199,plunger body 140, and core 142 are the components of the preferreddisplacement member of the present invention. In one embodiment, theplunger body 140 has an outer diameter in the range of 0.1 to 0.2 inches(more particularly 0.122 inches) and is approximately 0.5 to 2.5 incheslong. It should be appreciated that the plunger body 140 is any rodstructure of any length, depending on the application. The plunger body140 is positioned within an annular core 142, which has one larger endand one smaller end, and is attached to the core via any method known toordinary skill in the art, including epoxy, screw attachment, pinned, orwelded. The outer diameter of the larger end of the core 142 is in therange of 0.3 inches to 0.5 inches (and more particularly 0.395 inches),the thickness is in the range of 0.03 to 0.15 inches (and moreparticularly 0.05 to 0.10), and the length is in the range of 0.50 to1.75 inches long (and more particularly 1.05 inches). The small end ofthe core 142 has a diameter of 0.1 to 0.4 inches, and more particularly0.25 inches.

At least partially encompassing the small end of the core is a coilbobbin 195, which keeps the coil 148 in place and provides dimensionalstability to the coil 148. A gap preferably exists between the coilbobbin 195 and core 142. The size of the gap is approximately 0.01 to0.03 inches (and more particularly 0.02 inches). The coil bobbin 195 is,in one embodiment, a glass filled nylon structure, which should benonmetallic and non-ferromagnetic. The coil bobbin 195 is an annularstructure with an outer diameter of a size sufficient to provide a tightfit into the housing bore and an inner diameter sufficient to enclosethe core such that it has room to move and undergo some degree ofthermal expansion. The two end caps 130, 160 wedge the bobbin 195 intoplace and keep it from moving or slipping, particularly when exposed toelectromagnetic forces.

The plunger body is made of metal or non-metal material, such as brassor fiberglass, and the core is also made of metal, particularly steel1018 or 1117. Preferably, the plunger body is non-magnetic and the corebody is ferrous-magnetic. As discussed further below, the plunger body140 and core 142 are moved by the mechanism for moving the displacementmember, as further described below.

The mechanism for moving the displacement member comprises a largemagnet component, a small magnet component and a housing within whichthe magnets and a portion of the displacement member, namely the plungerbody 140 and core 142, are contained. More particularly, referring toFIG. 1, the mechanism to moving the displacement member comprises alarge magnet end cap, to hold and align the large magnet, 130, a largemagnet 132, an elastic material 134, a gap 197, a coil 148, a smallmagnet component 162, a small magnet mount and end cap 160, and anelastic material 164.

The large magnet end cap 130 holds and aligns the large magnet component132 and coil bobbin 195 in place within a housing 170, referred to asthe actuator body which has a borehole through which the componentsdescribed herein are placed. The large magnet component 132 needs to beproperly aligned with the core 142, plunger body 140, and small magneticcomponent 162 to ensure the proper movement of the displacement member.Both end caps 130 and 160 secure the coil bobbin 195 and coil 148 inposition. Additionally, a mounting plate can be used to capture and holdend cap 130. In one embodiment, the mounting plate is positionedvertically and flush against the side of the end cap and between the endcap and bore. The mounting plate has a hole in it, roughly same size asthe smaller diameter of the end cap. A clamping mechanism holds the bodyagainst the plate; alternatively the plate can be permanently fixed,using any boding technique known to persons of ordinary skill in theart. Unlike the prior art, such as U.S. Pat. No. 6,836,201, in apreferred embodiment, the magnets are located inside, not outside, thebore and provide bearings for the plunger, as discussed below.

The large magnet component 132 is separated from the core 142 by a gap197 and elastic material 134, such as a silicone washer, which, in oneembodiment, has an outer diameter of 0.3 to 0.5 inches (and moreparticularly 0.37 inches), an inner diameter of 0.1 to 0.3 inches (andmore particularly 0.188 inches), a thickness of 0.005 to 0.015 inches(and more particularly 0.01 inches), and a durometer of 35 to 45 (andmore particularly 40). The small magnet component 162 is separated fromthe core by an elastic material 164, such as a silicone washer, which,in one embodiment, has an outer diameter of 0.1 to 0.4 inches (and moreparticularly 0.24 inches), an inner diameter of 0.1 to 0.3 inches (andmore particularly 0.188 inches), a thickness of 0.005 to 0.015 inches(and more particularly 0.01 inches), and a durometer of 35 to 45 (andmore particularly 40). The small magnetic component 162 is held and keptproperly aligned within the housing 170 by a small magnet mount and endcap 160. The small magnet end cap screws 172 also serve to capture andhold in place the small magnet end caps 160.

Referring to FIG. 1, the valve system of the present invention furthercomprises a coil driver circuit board 150, which drives the actuator,comprising coil 148, and is preferably mounted to the actuator body 170via small screws, a coil driver connector 154, and an optical sensor152, which senses the position of the large end of the core 196. Coil148 serves to effectuate changes in magnetic fields in order to causemovement of the core 142 and plunger body 140. In one embodiment, thecoil is approximately 0.05 to 1.5 inches long (and more particularly 1inch long), has an outer diameter of 0.35 to 0.55 inches (and moreparticularly 0.46 inches), and an inner diameter of 0.15 to 0.35 inches(and more particularly 0.26 inches), with six layers of wire 29 AWGwire. The various elastic materials used in the displacement member andmechanism for moving the displacement member to provide a “soft” stop tothe movement of the rod 140 when the valve opens or closes. Inparticular, it serves to ensure the movement of the core does not damagethe magnets.

The large magnet component 132 can be one unitary magnet or, in apreferred embodiment, comprised of a plurality of magnets, such asthree. The small magnet component 162 can also be unitary or comprisedof a plurality of magnets. In one embodiment, the magnets are made of ispreferably Alnico, Samarium Cobalt, Neodymium, Rare Earth, or Ceramicmagnets. In one embodiment, the large magnet 132 is a Neodymium ringmagnet with an outer diameter of 0.2 to 0.5 inches (and moreparticularly 0.375 inches), an inner diameter of 0.05 to 0.3 inches (andmore particularly 0.125 inches), and a length of 0.2 to 0.5 inches (andmore particularly 0.375 inches). In one embodiment, the small magnet 162is made of Neodymium ring magnet, with an outer diameter of 0.15 to 0.4inches (and more particularly 0.25 inches), an inner diameter of 0.05 to0.3 inches (and more particularly 0.125 inches), and a length of 0.15 to0.4 inches (and more particularly 0.25 inches). The larger magnet 132 isused closer to the orifice closing member because the size is necessaryto generate sufficient opposition force to the valve seat. Further, theactuation force caused by the actuation coil is substantial equal eventhough the magnets are different size, thereby enabling a simple coildriver circuit.

In one embodiment, the rod, plunger or other elongated member 140 usesthe magnets' center holes as a linear bearing. Accordingly, the magnets'center holes should preferably have a bearing surface, such as chrome orany smooth hard surface with minimal friction. A gap is placed betweenthe coil bobbin 195 and the core 142 because of thermal expansion of thebobbin, bobbin creepage over time, and bobbin, core, and magnetstolerances. However, under all operating conditions, the gap should besufficient such that the plunger body 140 can move freely and not bindin the openings of the magnets and coil. In a preferred embodiment, thegap is approximately 0.01 to 0.06 inches (and more particularly 0.02inches) at room temperature.

When the valve is closed, referring to FIG. 2, the valve system of thepresent invention 200 controls fluid flow through a fluidic flow channel202, which is bounded by valve seats 204, by compressing the orificeclosing member, e.g. diaphragm 206, and thereby obstruct valve annularorifice 203. In a closed state, the main body of the diaphragm 206 ispressed against the valve seats 204 and, accordingly, substantiallyeliminates gap 198 (seen in FIG. 1).

Once just adjacent to the diaphragm 206, the displacement member nowcompresses the diaphragm 206. In particularly, plunger cap 210 has movedto compress the diaphragm 206. The plunger cap 210 has moved because achange in magnetic fields causes the core body 242 to move toward thelarge magnet component 232. The core body 242 stops moving when the corehead 296 passes through the gap 197 (in FIG. 1) and stops at the elasticmaterial 234 positioned adjacent to the large magnet component 232.Movement of the core 242 causes the plunger body 240, to which the core242 is bonded, to move as well. Movement of the plunger body 240 causesthe plunger head 299 to move within the plunger cap 210, pass throughthe gap 114 (in FIG. 1), and compress the spring 212. After a certainamount of compression, the plunger cap 210 moves and compresses thediaphragm 206. Movement of the plunger cap 210 creates a new gap 292between the cap body 210 and the elastic material 220 that is positionedadjacent to the large magnet end cap 230.

As shown in FIG. 2, the other components of the valve remain the same,including the actuator body 270, coil driver circuit 250, coil connector254, coil 248, coil bobbin 293, small end cap screws 272, optical sensor252, small magnet end cap 260. It should be appreciated however, that,by virtue of the core 242 movement, a gap 295 is created between thesmaller end of the core 294 and the elastic material 264, which ispositioned adjacent to the small magnetic component 262.

It should be appreciated that, to close the valve, the displacementmember applies a force to the orifice closing member, e.g. diaphragm206. The force required, from the displacement member, to deform thediaphragm to the point where the diaphragm touches the valve seat issubstantially linear and can be modeled as a linear spring. However, theforce requirements increase exponentially as the diaphragm is compressedinto the valve seat. Thus, the force profile for the displacement memberbecomes nonlinear and far more complex. Accordingly, there are severalunique challenges associated with the design of the valve and thetolerances between the various components of the displacement member,the orifice closing member, and the hard stop of the displacementmechanism. The displacement mechanism must be able to deliver thenonlinear force profile without permanently deforming the diaphragm.This means that the mechanism must deliver just the right amount offorce.

As discussed above, the displacement member comprises a rod, plunger orother elongated member that is bonded to another structure, referred toas a core, which has a larger diameter and can function as a stopperwhen forced up against another structure, such as a magnet face. One ofordinary skill in the art should appreciate that the displacement memberor moveable member is not limited to a rod and cylinder configuration.On the contrary, it can include non-cylindrical structures, unitarypieces, or multiple pieces that are welded or, in any other manner,bonded together. In sum, the displacement member can comprise manydifferent structures, provided the movement of the member can exert therequisite force on the orifice compressing member in a manner that isreliable and consistent.

For example, referring to FIG. 4, an alternate, less preferredembodiment is shown. For kidney dialysis applications, this embodimentdoes not typically reliably maintain the valve in a closed state. Thedisplacement member 400 comprises a housing 405 that includes anelectromagnet 410 with a substantially cylindrical structure and aborehole 415 running through it. The electromagnet 410 is securelypositioned centrally within the housing 405 by non-magnetic spacers 420which, in one embodiment are the end caps. The end caps have twopurposes—hold the magnets in place and sandwich the coil in place. Inone embodiment, elements 431 and 420 comprise a first unitary piece and405 and 420 comprise a second unitary piece. A cylindrically shapedferromagnetic core 425, having a first face 423 and a second face 424,is positioned to allow a portion of the core 425, between the first face423 and the second face 424, to have a linearly slide-able fit with thebore 415. The second face 424 is sufficiently larger than the bore 415thereby restricting the linear motion of the core 425. In oneembodiment, the second face is differently sized relative to the firstface to generate sufficient magnetic to keep the valve in a closedposition. The core 425 is capable of left and right linear slidingmotion within the bore 415.

Two differently sized magnets 430, 435 are also affixed within and atthe two end caps 431, 432 of the housing 405. The first face 423 of thecore 425 contacts with the first magnet 430 to form a first stable stateof the displacement system 400 and the second face 424 of the core 425contacts with the larger magnet 435 to form a second stable state of thedisplacement system 400. The placement of the permanent magnets 430, 435is designed to be within the diameter of housing 405, as it reduces thesize of the displacement system 400. A first rod 440 connected to thefirst face 423 of the core 425 passes through the first magnet 430thereby protruding from the housing 405 at one end and a second rod 445connected to the second face 424 of the core 425 passes through thesecond magnet 435 thereby protruding from the housing 405 at the otherend. The rods 440, 445 can be made of non-corrosive, non magnetic,material known in the art, such as but not limited to, brass. While oneembodiment has two rods connected to two faces of the core, in analternate embodiment there is only one rod connected to one of the facesof the shuttle.

Persons of ordinary skill in the art would appreciate that the magneticforce exerted by the electromagnet 410 on the core 425 is sufficientlyhigh to overcome the retention force of the permanent magnets 430, 435so that the displacement system 400 can be changed from the first stablestate to the second. Moreover, one of ordinary skill in the art wouldappreciate that the rod/plunger 445 moves with the core 425, therebycreating the motive force to compress or decompress the orifice closingmember. However, this embodiment has been determined to be inferior tothe first embodiment because it fails to sufficiently hold the closedstate.

Several design features of the orifice closing member operating inconjunction with the displacement member and mechanism should beappreciated. First, referring to FIG. 5, and as discussed above inrelation to FIGS. 1 and 2, a gap exists between the plunger cap 504 andthe orifice closing member 505, in particular the first diaphragm face505. The gap is in the range of 0.040 to 0.070 inches and moreparticularly approximately 0.055 inches. The diaphragm comprisessilicone, preferably a thickness of 0.040 inches, and can be modeled asa spring (K_(V2)) having a spring constant of 270 lbf/in. The seconddiaphragm face 506 is separated from the valve seat 507 and acted uponby magnetic forces modeled as a spring, K_(V1) having a spring constantof approximately 22.5 lbf/in and a thickness of approximately 0.047inches.

The rod 504 translates the force generated by the magnetic attraction ofthe core 501 to the magnet 503 modeled by spring Kp, which is separatedfrom the core head 501 by a washer, e.g. 0.010 inches of silicone in aclosed state and is separated from core head 501 by approximately 0.110inches in an open state. This silicone washer provides forces which aremodeled as a spring, K_(SL). The core 501 is bonded to the rod 504. Whenthe valve is actuated, the rod 504 moves in the direction of the valveseat 507 because the core, to which the rod is bonded, moves in thedirection of the large magnet 503.

Referring to FIG. 5, K_(V2) and K_(SL) correspond to elastic material,such as silicone, which are modeled as rigid springs. It should beappreciated that, when a valve is in a closed state, there are twopositions of importance. First, is the position of the rod against thediaphragm and the second is the position of the core face against thelarge magnet. When the valve is closed, the rod is pressing on the valvediaphragm with enough force to resist at least 600 mmHg back pressuregenerated within the fluid passage of the kidney dialysis system. Inthis embodiment, fluid pressures can reach 2600 mmHg and this system isdesigned to maintain the diaphragm firmly pressed against the valve seatto seal the orifice up to and including 2600 mmHg.

Additionally, when the valve is closed, the core's large face is pulledclose to, or directly against, the large magnet. The magnetic attractionof the core to the large magnet generates the force that the rod appliesto the orifice closing member, e.g. diaphragm. To generate a consistentand reliable force, the spacing between the core face and the face ofthe large magnet must be consistent. Therefore, it is preferred to placean elastic material 502, 503 between the core face 501 and the magnetface 504. The elastic material has a nonlinear spring constant and willcompress until the resultant forces for the elastic material equals themagnetic forces. When the rod applies force to the diaphragm via thecore, the core will experience the resultant force. For a staticcondition to occur, the sum of these forces on the core must equal zero.Furthermore, the elastic material serves to protect the magnet face fromchipping or breakage during actuation.

Referring to FIG. 7, when the valve 700 is in a closed state, the corehead 705, 702 has moved away from the small magnet face 701 (fromposition 702 a to position 702). When in position 702, the core head isseparated from the small magnet 701 by an elastic material 717, such asa silicone washer having a thickness of approximately 0.015 inches. Whenin position 705, the core head will have moved approximately0.140+/−0.20 inches, including a distance of 0.45+/−0.005 inches duringwhich the rod 708 does not move, and stopped against an elastic material716 (e.g. a silicone washer having a thickness of approximately 0.015inches), which separates the core head 705 from the large magnet face706. The large magnet 706 is, in turn separated from the rod head 707.

When the valve is in an open state, the large magnet 706 is separatedfrom the rod head 707 by an elastic material 715, such as a siliconewasher having a thickness of approximately 0.015 inches. When the valveis in a closed state, the large magnet 706 is separated from the rodhead 707 by an elastic material 715, such as a silicone washer having athickness of approximately 0.015 inches and a distance of approximately0.055+/−0.10 inches. When the valve is closed, the rod head 707 hasmoved from being proximate to the large magnet 706 and elastic material715 to being proximate to the valve seat 710. Specifically, the rod head707 moves to compress the diaphragm 708 and thereby press against anelastic material 709 (e.g. silicone having a thickness of approximately0.040 inches) which, in turn, presses against the valve seat 710. Thiscauses the valve to close with an approximate force of 14 N.

It should be appreciated that the configuration of the displacementmember and mechanism relative to the orifice closing member and thetolerances described herein provide for a diaphragm displacement profile600, as shown in FIG. 6 which is suitable for applications that need toresist at least 600 mmHg back pressure, such as kidney dialysis systems.Referring to FIG. 6, an exemplary diaphragm displacement profile isprovided, where the force 602 exerted by the displacement member isprovided on the y-axis and the corresponding diaphragm displacement isprovided on the x-axis. The inflection point on this curve 603 indicateswhen the diaphragm starts being compressed against the valve seat. Tothe left of the inflection 603, the diaphragm is being forced to flextoward the valve seat, but there is no substantial compression againstthe valve seat. To the right of the inflection point 603, the diaphragmis flexed against the valve seat, deforming the diaphragm material andaffecting a good seal against the fluid pressure.

Another important component of the displacement mechanism system is anactuator system. Referring to FIG. 3, during the actuation process,coils 305 are energized and the magnetic field builds, thus creatingmagnetic force opposing the small magnet attraction force. As the forcebuilds, the core, discussed above, starts to move to the close position(large magnet). Once the core moves past a point of no return, theattraction forces on the core of the large magnet has overcome theattraction forces of the small magnet. To ensure that the opposingforces caused by the valve diaphragm do not overcome the attractionforce of the large magnet, a gap is provided, as discussed above.

The coil design is made of coil form and magnet wire. The size of thecoil form size is preferably based upon commercially available coilforms the pulsed current capability of the power supply, and, inparticular, the required actuation force and the power supply voltage.The actuation force is proportional to the amp-turn rating of the coil.In one embodiment, it is preferred to limit the coil current to 6amperes or less.

Factors important in the coil design include the number of layers,packing factor, wire diameter, and coil resistance. In one embodiment,the present invention uses a bobbin with 6 layers of wire andapproximately 0.010 inches space between the bobbin flange diameter andthe last layer. With an insulation requirement of heavy poly nylon and acoil resistance of 3.5+/−0.5 Ohms, the wire size is approximately 29AWG. Any size coil form can be used.

The circuit used to drive the coil is an H-bridge circuit which enablescurrent to be reversed for open and closed operations. The H-Bridgecircuit is driven via a unique pulse width modulated (PWM) signal. ThePWM signal is used to generate a cosine current pulse through the coil.The period of the cosine pulse is related to the mass of the core andthe opposing force. The preferred embodiment does not use a bipolar DCpower switch or sense switch; rather, the optical sensor operates todetermine the position of the core, conclude the valve state, andgenerate an electronic drive cosine waveform to move the plunger in thedesired direction, thereby changing the state of the valve.

Optionally, as shown in FIGS. 1 and 2 as elements 152, 252, the valvesystem uses a sensor, preferably an optical sensor, to determine thestate of the valve (open or closed). This can be achieved by positioningthe optical sensor in a location that has a sufficient difference inreflectivity, or other optical properties, between a valve open stateand a valve closed state. For example, when the valve is closed, in oneembodiment, the large end of the core 296 is positioned against anelastic material 234 and the large magnet component 232. The large endof the core 296 has a width wide enough to be sensed by a reflectiveoptical sensor, but not too wide so the optical sensor has positionresolution. The optical sensor will be placed on the outside of thedisplacement member/mechanism and look through its body, which ispreferably made of transparent polycarbonate. The optical sensor'swavelength will be in the near infrared range (NIR) so as to have goodtransmission through the polycarbonate body. One of ordinary skill inthe art would appreciate that the sensor can be chosen to suit anymaterial structure, provided it includes the appropriate filters. Here,the optical sensor preferably has built into it a long pass opticalfilter for NIR responsivity.

Functionally, when the core is in the open position, as shown in FIG. 1,the large end of the core 196 moves out of the field of view of theoptical sensor 152, thus very little reflection will be seen by theoptical sensor. When the large end of the core 296 is in the field ofview, as shown in FIG. 2, there will be a reflection that the sensorwill see, thus indicating the core is in the closed position. One ofordinary skill in the art would appreciate that the sensor can bepositioned such that it senses a great deal of reflectivity from thecore when the valve is in the open position and much less reflectivity(because the core is moved out of the field of view) when the valve isin the closed position. Further, one of ordinary skill in the art wouldappreciate that the sensor could be positioned proximate to the gap tosense when the gap is present and when the gap is absent, therebyindicating the state of the valve.

Operationally, as referred to in FIG. 8, a valve is initially one of twostates, open or closed. Assuming the valve is in an open state 801, thefirst step in closing the valve is to energize the coil driver circuit802 and thereby cause the magnetic field generated by the coil to passthrough the core, create an opposing magnetic force between the core andsmall magnet, and create a weak attraction force between the largemagnet and the large end of the core. As the displacement member startsto move 803, the small magnet attraction force diminishes as the largemagnet attraction forces increases. The displacement member moves 803until a point of no return, after which the displacement member 804closes a gap 804 and compresses the orifice closing member, namely thediaphragm 805, against the valve seat 806. The compression of thediaphragm 806 causes the diaphragm to close the orifice 807 and closethe valve 808.

Referring to FIG. 8, assuming the valve is in a closed state 809, thefirst step in opening the valve is to energize the coil driver circuit810 and thereby cause the magnetic field generated by the coil to passthrough the core, create an opposing magnetic force between the core andlarge magnet, and create a weak attraction force between the smallmagnet and the small end of the core. As the displacement member startsto move 811, the large magnet attraction force diminishes as the smallmagnet attraction forces increases. The displacement member moves 811until a point of no return, after which the displacement memberdecompresses the diaphragm 812 away from the valve seat 813. The orificeopens by virtue of no longer being covered by the diaphragm 814. Thedisplacement member returns to its original position and recreate thegap 815.

Since the first and second stable states of the core are maintained evenwhen power to the electromagnet is switched off, this allows for thedisplacement system to have low power consumption and low heatgeneration relative to prior art actuators where continuous power supplyis needed to maintain states, additionally resulting in high heatgeneration.

While there has been illustrated and described what is at presentconsidered to be a preferred embodiment of the present invention, itwill be understood by those skilled in the art that various changes andmodifications may be made, and equivalents may be substituted forelements thereof without departing from the true scope of the invention.In addition, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the central scope thereof. Therefore, it is intended thatthis invention not be limited to the particular embodiment disclosed asthe best mode contemplated for carrying out the invention, but that theinvention will include all embodiments falling within the scope of theappended claims.

I claim:
 1. A kidney dialysis system comprising: a valve having a firststate and a second state wherein: the valve comprises a first magnet anda second magnet; the valve comprises a displacement member positionedsuch that the first magnet and second magnet provide a bearing surfacefor movement of the displacement member; the valve comprises elasticmaterial positioned between a surface of the first magnet and thedisplacement member and positioned between a surface of the secondmagnet and the displacement member; the valve is configured such that aninput of energy into the valve modulates magnetic fields of the firstmagnet and the second magnet which cause the displacement member to movewithin the kidney dialysis system; the movement of the displacementmember causes a change between the first state and the second state; anda maintenance of the first state or second state does not require energyinput.
 2. The kidney dialysis system of claim 1 further comprising: adisposable manifold having an orifice wherein the orifice is adapted tobe closed to fluid flow when the valve is in the first state and whereinthe orifice is adapted to be open to fluid flow when the valve is in thesecond state.
 3. The kidney dialysis system of claim 2 wherein the valvecomprises a compressible material and wherein the compressible materialis configured to cover the orifice.
 4. The kidney dialysis system ofclaim 3 wherein the movement of the displacement member compresses thecompressible material into the orifice when the valve is in the firststate.
 5. The kidney dialysis system of claim 3 wherein the displacementmember is configured such that the movement of the displacement membercauses the compressible material to expand out of the orifice when thevalve is in the second state.
 6. The kidney dialysis system of claim 2wherein the valve further comprises an orifice closing member, whereinthe orifice closing member is configured to cover the orifice, andwherein the orifice closing member is configured to compress against avalve seat when the valve is in a closed position.
 7. The kidneydialysis system of claim 6 wherein the displacement member is adapted tobe physically movable relative to the orifice closing member, whereinthe displacement member is adapted to move from a second position whenthe valve is in an open position to a first position and wherein, in thefirst position, the displacement member is adapted to press against theorifice closing member to cause the orifice closing member to compressagainst the valve seat.
 8. The kidney dialysis system of claim 6,wherein the orifice closing member and valve seat are part of adisposable manifold for the kidney dialysis system.
 9. The kidneydialysis system of claim 1, wherein the valve further comprises anactuator configured to generate capable of generating an electromagneticforce, wherein the electromagnetic force is adapted to reverse thedirection of the magnetic fields.
 10. The kidney dialysis system ofclaim 1, wherein the first magnet, having a first pole, is larger thanthe second magnet, having a second pole.
 11. The kidney dialysis systemof claim 10, wherein the first pole and second pole repel each other andwherein the first magnet and second magnet are configured to have thefirst pole and second pole face each other.
 12. A kidney dialysis systemcomprising: a disposable manifold having at least one orifice covered bya compressible material; and a moveable displacement member positionedoutside the disposable manifold and configured to move between a firststate and a second state; a first magnet and a second magnet positionedoutside the disposable manifold and configured to provide a bearingsurface for movement of the moveable displacement member; and elasticmaterial positioned between a surface of the first magnet and themoveable displacement member and positioned between a surface of thesecond magnet and the moveable displacement member, wherein the firstmagnet and second magnet generate ft magnetic fields, wherein an inputof energy modulates the magnetic fields, and wherein maintenance of thefirst or the second state does not require energy input.
 13. The kidneydialysis system of claim 12, wherein the orifice is positioned within afluid pathway and wherein the fluid pathway is closed to fluid flow whenthe displacement member is in the first state and wherein the fluidpathway is open to fluid flow when the displacement member is in thesecond state.
 14. The kidney dialysis system of claim 13 wherein themovement of the displacement member compresses the compressible materialinto the orifice when the displacement member is in the first state. 15.The kidney dialysis system of claim 13 wherein the movement of thedisplacement member valve causes the material to expand out of theorifice when the displacement member moves from the first state to thesecond state.
 16. The kidney dialysis system of claim 12 wherein thecompressible material compresses against a valve seat when thedisplacement member is in the first state.
 17. The kidney dialysissystem of claim 12, wherein the first magnet is larger than the secondmagnet.
 18. The kidney dialysis system of claim 17, further comprisingan actuator configured to generate an electromagnetic force, whereinsaid electromagnetic force is adapted to reverse the direction of themagnetic fields.